Some terrains are more prone to have sinkholes developing: limestone, salt beds, gypsum are types of rock below the land surface where groundwater can easily circulate and, over time, slowly dissolve the rock, forming cavities that, once large enough, will collapse due to the weight of the ground above.
In this case study, the area was well known for sinkhole occurrences since it is the site of an old salt mine creating ideal conditions for cavities to form over years and who could tune into sinkholes. That old salt mine location is surrounded by roads, a residential area, and an interstate railroad, a critical transportation link in the Midwest of the US. The chosen solution was to install a fiber optic cable in a trench that would cover the critical area (see pic #1) and automatically alert the authorities via cellular phone if something happened so the authority could quickly evacuate an area or shut down railroad activities until site inspection is performed and the situation is being taken care of.
A 12km loop Fiber Optic cable was linked to a Distributed Fiber Optic readout unit (DiTeST), installed on-site, and scanned 24/7 for any signs of ground movement. The fiber optic cable is very sensitive, detecting very minor strain changes that would happen should the earth collapse, pulling at the same time the fiber optic cable. That technology not only enables us to detect ground movement but also to localize the ground movement with a 1m precision, pinpointing the exact position of the event along the 12km loop. Our DiView software enables easy viewing and parametrization of the monitoring system.
To read the full article about this project go to: https://roctest.com/wp-content/uploads/2017/01/P43.pdf
For more information about this case study or our product offering, please contact us.